Discrepancy in Neutron Lifetime Still Unresolved

Discrepancy in Neutron Lifetime Still Unresolved

Outside of the nucleus, the proton remains stable for at least 1034 years, but an isolated neutron survives just 15 minutes before it decays into a proton, electron, and an antineutrino. Astrophysicists rely on a precise value of the free neutron lifetime to calculate the rate of nucleosynthesis during the big bang, while particle physicists use it to constrain fundamental parameters of the standard model. Yet measured lifetimes have varied by about a percent, depending on the experimental technique. As reported in Physical Review Letters, the latest refinement of the neutron lifetime in one type of experiment has left this discrepancy unresolved.